# 74.7 根据环境改变配置

一个YAML文件实际上是一系列以`---`线分割的文档，每个文档都被单独解析为一个平坦的（flattened）map。

如果一个YAML文档包含一个`spring.profiles`关键字，那profiles的值（以逗号分割的profiles列表）将被传入Spring的`Environment.acceptsProfiles()`方法，并且如果这些profiles的任何一个被激活，对应的文档被包含到最终的合并中（否则不会）。

示例：

```yaml
server:
  port: 9000
---

spring:
  profiles: development
server:
  port: 9001

---

spring:
  profiles: production
server:
  port: 0
```

在这个示例中，默认的端口是`9000`，但如果Spring profile `development`生效则该端口是`9001`，如果`production`生效则它是`0`。

**注** YAML文档以它们出现的顺序合并，所以后面的值会覆盖前面的值。

想要使用profiles文件完成同样的操作，你可以使用`application-${profile}.properties`指定特殊的，profile相关的值。


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